This invention relates to a vegetation cutting tool and to a blade therefor.
Although a main use for the present invention and the following description is in relation to a vegetation cutting tool known as a brush cutter, it is to be understood that as used herein the expression xe2x80x9cvegetation cutting toolxe2x80x9d is not limited to a tool for use with a brush cutter per se. It is to be understood to refer in general to cutting tools which connect to a rotating shaft in a variety of cutting appliances such as, for example, brush cutters, lawn or grass mowers, garden edgers etc.
A brush cutting tool including a circular hub and a nylon cord is well known. As the hub spins on the shaft of a brush cutter, the nylon cord assumes a radial orientation due to centrifugal force and acts as the cutting member. A major drawback with nylon cord brush cutting tools is that the cord lacks robustness and must be regularly replaced. Furthermore, nylon cord brush cutters struggle to cut through tougher weeds and other vegetation.
Also known is a brush cutting tool including a circular hub and a fixed radial blade member. Whilst such arrangements can generally deal with tougher weeds and are more robust than the nylon cord cutters, they suffer a number of disadvantages including the undesirable tendency to transmit impact shock to the brush cutter in the event that the blade member strikes a rock or the like.
Also known are grass mowers having as the cutting tool a hub with blade members mounted thereto.
In one aspect this invention resides broadly in a vegetation cutting tool including:
a hub adapted to be mounted on the shaft of a vegetation cutter or the like for rotation therewith, and
a blade removably mounted to the hub, the blade being manually movable between an operative cutting position and a dismount position in which the blade can be dismounted from the hub.
In the preferred embodiment movement of the blade from the operative position to the dismount position involves pivoting of the blade relative to the hub and translation of the blade relative to the hub.
In the preferred embodiment said translation prior to said pivoting is prevented by abutment means such that said pivoting must occur first.
In the preferred embodiment the blade and the hub are mounted together via a post and slot arrangement. The hub preferably includes a post having an enlarged head and the blade includes a slot dimensioned to receive the post, the slot having an enlarged portion adapted to receive the enlarged head of the post. The slot preferably extends in a generally radial direction when the blade is in the operative position and the enlarged portion of the slot is located at the radially outer end of the slot. It is preferred that in said dismount position, the enlarged portion of the slot is aligned with the enlarged head of the post. Preferably the enlarged head is eccentric with respect to the post and the enlarged portion of the slot is offset from the centreline of the slot.
In another aspect the invention resides in a blade for a rotating vegetation cutting tool, the blade including:
first end including means for mounting the blade to the vegetation cutting tool; and
a second end having a radius of curvature less that the radius of the cut made by the blade in use.
Preferably, the radius of curvature of the second end of the blade is between 25 to 75 percent of the radius of the cut made by the blade in use. In the preferred embodiment the radius of curvature of the second end of the blade is approximately 50 percent of the radius of the cut made by the blade in use.
It is preferred that the blade includes cutting edges extending between the first and second ends, the cutting edges diverging towards the second end. The blade may also include a cutting face inclining inwardly of the cutting edges.
Preferably the cutting edges have opposed cutting faces inclining inwardly of each cutting edge. The blade may also include abutment faces extending inwardly from the circumferentially opposed end points of the second end to meet respective cutting faces, said abutment faces being substantially parallel to the axis of rotation of the vegetation cutting tool.
In another aspect the invention resides in a blade for a rotating vegetation cutting tool, the blade being manually removable from the vegetation cutting tool.
In another aspect the invention resides in a blade for a rotating vegetation cutting tool, the blade including:
a first end including means for mounting the blade to the vegetation cutting tool;
a second end; and
cutting edges extending between the first and second ends, the cutting edges diverging towards the second end.
In another aspect this invention resides broadly in a blade for a rotating vegetation cutting tool, the blade including:
first end including means for mounting the blade to the vegetation cutting tool;
a second end;
cutting edges extending between the first and second ends, and
opposed cutting faces inclining inwardly of each cutting edge.
In another aspect this invention resides broadly in a blade for a rotating vegetation cutting tool, the blade including:
a first end including means for mounting the blade to the vegetation cutting tool;
a second end;
cutting edges extending between the first and second ends;
cutting faces inclining inwardly of said cutting edges, and
abutment faces extending inwardly from the circumferentially opposed end points of the second end to meet respective cutting faces, said abutment faces being substantially parallel to the axis of rotation of the vegetation cutting tool.
In another aspect the invention resides in a vegetation cutting tool including a blade as defined above.
In another aspect this invention resides in a vegetation cutting tool including:
a hub adapted to be mounted on the shaft of a vegetation cutter or the like for rotation therewith;
a link member pivotably mounted with respect to the hub; and
a blade member pivotably mounted with respect to the link member;
wherein the hub includes two diametrically opposed lobes, each lobe including mounting means for pivotably mounting a link member.
Preferably, the link member is pivotably mounted with respect to the hub for relative rotation about a first axis and the blade member is pivotably mounted with respect to the link member for relative rotation about a second axis, the first and second axes being spaced and parallel. Preferably also, the hub, link member and blade member lie in a common plane, the plane being perpendicular to the first and second axes. Also the link member preferably includes a pair of spaced arms which straddle the hub and the blade member.
Preferably, the hub, link member, and blade member jointly define a leading edge adapted to cut vegetation, and wherein the leading edge is shaped such that cut vegetation may slide outwardly along the leading edge.
It is also preferred that there is a smooth transition between the portion of the leading edge defined by the hub and the portion of the leading edge defined by the link member. Also there is preferably a smooth transition between the portion of the leading edge defined by the link member and the portion of the leading edge defined by the blade member.